Mobile phone camera is becoming an essential part of mobile phones. Today, it is difficult to find a mobile phone without a digital camera. In the near future, it is expected that the majority of mobile phones or smart phones will have two cameras, a primary high resolution mega-pixel camera for photography and a video graphics array camera for video calls. As the market for mobile phones continues to grow at an explosive rate, the demand for mobile phone cameras is expected to be high. The expectation for mobile phone cameras is that they will get better and cheaper, and they will remain an integral part of the mobile phone. Current mobile phone cameras consist of greater than 10 different components including plastic or glass molded lenses, pupils, baffles, actuators, lens holders, lens barrel, color filters, and image sensors. These components are being manufactured and assembled by many different suppliers, thus, the unit costs are relatively high. The wafer level camera is the anticipated next generation mobile phone camera. Wafer level camera is considerably simple than current phone cameras and offers up to 50% manufacturing cost reduction. All components are produced on an 8″ wafer. The wafer-level-optic lens is mounted together with the CMOS (Complementary metal oxide semiconductor) wafer, and the wafer stack is diced into the individual camera modules.
The two major advantages wafer level cameras offer to mobile phone makers over traditional image sensors are large cost reductions, and reductions in size. The cost reduction potential of wafer level camera has driven major mobile phone companies to promote wafer level camera as the ultimate technology for next generation low cost mobile phone cameras.
One of the major challenges for ultraviolet micro lithography in making optical wafers by the replication method is the lack of suitable photopolymer materials. For a photopolymer material to be suitable for wafer-level-optic lens, it must be appropriate for high throughput imprint lithography, stable for solder reflow temperatures at about 260° C., optically clear, and display long lifetime stability in harsh environments (heat, humidity and sunlight). Moreover, for the lens designs, a choice of different lens materials with refractive indices of about 1.52 to about 1.65 at about 589 nm wavelength may be desired. Currently, most optically clear photopolymers do not meet both the requirement of high refractive index and stability at solder reflow temperatures.
What is needed is radiation-curable composition for making optically clear high refractive index materials that does not have the problems found in the current art.